What is a noted adverse effect of clozapine?

Clozapine, an atypical antipsychotic, is notably associated with a serious adverse effect known as hematologic reaction, specifically agranulocytosis, which is a significant decrease in the white blood cell count. This condition can lead to an increased risk of infections and is a major reason why patients on clozapine require regular monitoring of their blood counts. The risk of agranulocytosis with clozapine distinguishes it from many other antipsychotic medications, making close hematological monitoring essential during treatment.

While weight gain, parkinsonism, and insomnia can also occur with antipsychotic medications, they are more commonly associated with other drugs in the class or occur with a lower frequency. For example, weight gain is particularly a concern with several other atypical antipsychotics, while parkinsonism is more linked to first-generation antipsychotics. Insomnia can arise from various factors unrelated to clozapine specifically and is not considered a hallmark adverse effect of this medication. Thus, the hematologic reaction's severity and necessity for monitoring are what make it a notable adverse effect of clozapine.